ABSTRACT
Nonelectrostatic repulsion between neutral hydrophilic particles suspended in water was first observed by Joffe and Mudd in 1935 with particle suspensions of a smooth strain of Salmonella typhi. Polar forces are defined here as the forces operating in electron acceptor/electron donor or Lewis acid-base interactions. Polar forces are designated by the superscript acid-base, for acid-base interactions. The crucial role of (Lewis) acid-base interactions in interfacial interactions was first clearly identified by Fowkes. The underlying cause of these nonelectrostatic repulsion forces originates in the interplay between the hydrogen-bonding forces of liquid water and the polar or electron-accepting and electron-donating (Lewis acid-base) capacities of the surfaces of cells as well as bio- and other polymers. Polar forces are defined as the forces operating in electron acceptor/electron donor or Lewis acid-base interactions. Polar forces do not decay with distance in proportion to the square of that distance, but rather decrease at an exponential rate.
